buildkite/bazelci.py

# Copyright 2018 The Bazel Authors. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import print_function
import argparse
import base64
import codecs
import hashlib
import json
import os.path
import multiprocessing
import re
import shutil
import subprocess
import sys
import stat
import tempfile
import urllib.request
from shutil import copyfile
from urllib.parse import urlparse


def downstream_projects():
  return {
      "BUILD_file_generator": {
          "git_repository": "https://github.com/bazelbuild/BUILD_file_generator.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/BUILD_file_generator-postsubmit.json"
      },
      "bazel-toolchains": {
          "git_repository": "https://github.com/bazelbuild/bazel-toolchains.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/bazel-toolchains-postsubmit.json"
      },
      "buildtools": {
          "git_repository": "https://github.com/bazelbuild/buildtools.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/buildtools-postsubmit.json"
      },
      "CLion Plugin": {
          "git_repository": "https://github.com/bazelbuild/intellij.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/clion-postsubmit.json"
      },
      "Eclipse Plugin": {
          "git_repository": "https://github.com/bazelbuild/eclipse.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/eclipse-postsubmit.json"
      },
      "Gerrit": {
          "git_repository": "https://gerrit.googlesource.com/gerrit.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/gerrit-postsubmit.json"
      },
      "Google Logging": {
          "git_repository": "https://github.com/google/glog.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/glog-postsubmit.json"
      },
      "IntelliJ Plugin": {
          "git_repository": "https://github.com/bazelbuild/intellij.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/intellij-postsubmit.json"
      },
      "migration-tooling": {
          "git_repository": "https://github.com/bazelbuild/migration-tooling.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/migration-tooling-postsubmit.json"
      },
      "protobuf": {
          "git_repository": "https://github.com/google/protobuf.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/protobuf-postsubmit.json"
      },
      "re2": {
          "git_repository": "https://github.com/google/re2.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/re2-postsubmit.json"
      },
      "rules_appengine": {
          "git_repository": "https://github.com/bazelbuild/rules_appengine.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_appengine-postsubmit.json"
      },
      "rules_closure": {
          "git_repository": "https://github.com/bazelbuild/rules_closure.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_closure-postsubmit.json"
      },
      "rules_d": {
          "git_repository": "https://github.com/bazelbuild/rules_d.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_d-postsubmit.json"
      },
      "rules_go": {
          "git_repository": "https://github.com/bazelbuild/rules_go.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_go-postsubmit.json"
      },
      "rules_groovy": {
          "git_repository": "https://github.com/bazelbuild/rules_groovy.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_groovy-postsubmit.json"
      },
      "rules_gwt": {
          "git_repository": "https://github.com/bazelbuild/rules_gwt.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_gwt-postsubmit.json"
      },
      "rules_jsonnet": {
          "git_repository": "https://github.com/bazelbuild/rules_jsonnet.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_jsonnet-postsubmit.json"
      },
      "rules_k8s": {
          "git_repository": "https://github.com/bazelbuild/rules_k8s.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_k8s-postsubmit.json"
      },
      "rules_nodejs": {
          "git_repository": "https://github.com/bazelbuild/rules_nodejs.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_nodejs-postsubmit.json"
      },
      "rules_perl": {
          "git_repository": "https://github.com/bazelbuild/rules_perl.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_perl-postsubmit.json"
      },
      "rules_python": {
          "git_repository": "https://github.com/bazelbuild/rules_python.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_python-postsubmit.json"
      },
      "rules_rust": {
          "git_repository": "https://github.com/bazelbuild/rules_rust.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_rust-postsubmit.json"
      },
      "rules_sass": {
          "git_repository": "https://github.com/bazelbuild/rules_sass.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_sass-postsubmit.json"
      },
      "rules_scala": {
          "git_repository": "https://github.com/bazelbuild/rules_scala.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_scala-postsubmit.json"
      },
      "rules_typescript": {
          "git_repository": "https://github.com/bazelbuild/rules_typescript.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_typescript-postsubmit.json"
      },
      # Enable once is resolved: https://github.com/bazelbuild/continuous-integration/issues/191
      # "rules_webtesting": {
      #     "git_repository": "https://github.com/bazelbuild/rules_webtesting.git",
      #     "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/rules_webtesting-postsubmit.json"
      # },
      "skydoc": {
          "git_repository": "https://github.com/bazelbuild/skydoc.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/skydoc-postsubmit.json"
      },
      "subpar": {
          "git_repository": "https://github.com/google/subpar.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/subpar-postsubmit.json"
      },
      "TensorFlow": {
          "git_repository": "https://github.com/tensorflow/tensorflow.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/tensorflow-postsubmit.json"
      },
      "TensorFlow Serving": {
          "git_repository": "https://github.com/tensorflow/serving.git",
          "http_config": "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/pipelines/tensorflow-serving-postsubmit.json"
      }
  }


def python_binary():
  return "python3.6"


def bazelcipy_url():
  '''
  URL to the latest version of this script.
  '''
  return "https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/bazelci.py"


def eprint(*args, **kwargs):
  '''
  Print to stderr and exit the process.
  '''
  print(*args, file=sys.stderr, **kwargs)
  exit(1)


def platforms_info():
  '''
  Returns a map containing all supported platform names as keys, with the
  values being the platform name in a human readable format, and a the
  buildkite-agent's working directory.
  '''
  return {
      "ubuntu1404":
      {
          "name": "Ubuntu 14.04",
          "agent-directory": "/var/lib/buildkite-agent/builds/${BUILDKITE_AGENT_NAME}/"
      },
      "ubuntu1604":
      {
          "name": "Ubuntu 16.04",
          "agent-directory": "/var/lib/buildkite-agent/builds/${BUILDKITE_AGENT_NAME}/"
      },
      "macos":
      {
          "name": "macOS",
          "agent-directory": "/usr/local/var/buildkite-agent/builds/${BUILDKITE_AGENT_NAME}/"
      }
  }


def downstream_projects_root(platform):
  downstream_projects_dir = os.path.expandvars(
      "${BUILDKITE_ORGANIZATION_SLUG}-downstream-projects")
  path = os.path.join(agent_directory(platform), downstream_projects_dir)
  if not os.path.exists(path):
    os.makedirs(path)
  return path


def agent_directory(platform):
  return os.path.expandvars(platforms_info()[platform]["agent-directory"])


def supported_platforms():
  return set(platforms_info().keys())


def platform_name(platform):
  return platforms_info()[platform]["name"]


def fetch_configs(http_url):
  '''
  If specified fetches the build configuration from http_url, else tries to
  read it from .bazelci/config.json.
  Returns the json configuration as a python data structure.
  '''
  if http_url is None:
    with open(".bazelci/config.json", "r") as fd:
      return json.load(fd)
  with urllib.request.urlopen(http_url) as resp:
    reader = codecs.getreader("utf-8")
    return json.load(reader(resp))


def print_collapsed_group(name):
  print("\n--- {0}\n".format(name))


def print_expanded_group(name):
  print("\n+++ {0}\n".format(name))


def execute_commands(config, platform, git_repository, use_but, save_but,
                     build_only, test_only):
  exit_code = -1
  tmpdir = None
  bazel_binary = "bazel"
  try:
    if git_repository:
      clone_git_repository(git_repository, platform)
    cleanup(platform)
    tmpdir = tempfile.mkdtemp()
    if use_but:
      print_collapsed_group("Downloading Bazel under test")
      bazel_binary = download_bazel_binary(tmpdir, platform)
    print_bazel_version_info(bazel_binary)
    execute_shell_commands(config.get("shell_commands", None))
    execute_bazel_run(bazel_binary, config.get("run_targets", None))
    if not test_only:
      execute_bazel_build(bazel_binary, config.get("build_flags", []),
                          config.get("build_targets", None))
      if save_but:
        upload_bazel_binary()
    if not build_only:
      bep_file = os.path.join(tmpdir, "build_event_json_file.json")
      exit_code = execute_bazel_test(bazel_binary, config.get("test_flags", []),
                                     config.get("test_targets", None), bep_file)
      # Fail the pipeline if there were any flaky tests.
      if has_flaky_tests() and exit_code == 0:
        exit_code = 1
      upload_test_logs(bep_file, tmpdir)
  finally:
    if tmpdir:
      shutil.rmtree(tmpdir)
    cleanup(platform)
    if exit_code > -1:
      exit(exit_code)


def has_flaky_tests(bep_file):
  return len(test_logs_for_status(bep_file, status="FLAKY")) > 0


def print_bazel_version_info(bazel_binary):
  print_collapsed_group("Bazel Info")
  fail_if_nonzero(execute_command([bazel_binary, "version"]))
  fail_if_nonzero(execute_command([bazel_binary, "info"]))


def upload_bazel_binary():
  print_collapsed_group("Uploading Bazel under test")
  fail_if_nonzero(execute_command(["buildkite-agent", "artifact", "upload",
                                   "bazel-bin/src/bazel"]))


def download_bazel_binary(dest_dir, platform):
  source_step = create_label(platform_name(platform), "Bazel", build_only=True,
                             test_only=False)
  fail_if_nonzero(execute_command(["buildkite-agent", "artifact", "download",
                                   "bazel-bin/src/bazel", dest_dir, "--step", source_step]))
  bazel_binary_path = os.path.join(dest_dir, "bazel-bin/src/bazel")
  st = os.stat(bazel_binary_path)
  os.chmod(bazel_binary_path, st.st_mode | stat.S_IEXEC)
  return bazel_binary_path


def clone_git_repository(git_repository, platform):
  root = downstream_projects_root(platform)
  project_name = re.search("/([^/]+)\.git$", git_repository).group(1)
  clone_path = os.path.join(root, project_name)
  print_collapsed_group("Fetching " + project_name + " sources")
  if os.path.exists(clone_path):
    os.chdir(clone_path)
    fail_if_nonzero(execute_command(
        ["git", "remote", "set-url", "origin", git_repository]))
    fail_if_nonzero(execute_command(["git", "clean", "-fdqx"]))
    fail_if_nonzero(execute_command(
        ["git", "submodule", "foreach", "--recursive", "git", "clean", "-fdqx"]))
    # sync to the latest commit of HEAD. Unlikely git pull this also works after
    # a force push.
    fail_if_nonzero(execute_command(["git", "fetch", "origin"]))
    remote_head = subprocess.check_output(
        ["git", "symbolic-ref", "refs/remotes/origin/HEAD"])
    remote_head = remote_head.decode("utf-8")
    remote_head = remote_head.rstrip()
    fail_if_nonzero(execute_command(
        ["git", "reset", remote_head, "--hard"]))
    fail_if_nonzero(execute_command(
        ["git", "submodule", "sync", "--recursive"]))
    fail_if_nonzero(execute_command(
        ["git", "submodule", "update", "--init", "--recursive", "--force"]))
    fail_if_nonzero(execute_command(
        ["git", "submodule", "foreach", "--recursive", "git", "reset", "--hard"]))
    fail_if_nonzero(execute_command(["git", "clean", "-fdqx"]))
    fail_if_nonzero(execute_command(
        ["git", "submodule", "foreach", "--recursive", "git", "clean", "-fdqx"]))
  else:
    fail_if_nonzero(execute_command(
        ["git", "clone", "--recurse-submodules", git_repository, clone_path]))
    os.chdir(clone_path)


def cleanup(platform):
  print_collapsed_group("Cleanup")
  if os.path.exists("WORKSPACE"):
    fail_if_nonzero(execute_command(["bazel", "clean", "--expunge"]))


def execute_shell_commands(commands):
  if not commands:
    return
  print_collapsed_group("Setup (Shell Commands)")
  shell_command = "\n".join(commands)
  fail_if_nonzero(execute_command([shell_command], shell=True))


def execute_bazel_run(bazel_binary, targets):
  if not targets:
    return
  print_collapsed_group("Setup (Run Targets)")
  for target in targets:
    fail_if_nonzero(execute_command([bazel_binary, "run", "--curses=yes",
                                     "--color=yes", "--verbose_failurs", target]))


def execute_bazel_build(bazel_binary, flags, targets):
  if not targets:
    return
  print_expanded_group("Build")
  num_jobs = str(multiprocessing.cpu_count())
  common_flags = ["--curses=yes", "--color=yes", "--keep_going",
                  "--verbose_failures", "--jobs=" + num_jobs]
  fail_if_nonzero(execute_command(
      [bazel_binary, "build"] + common_flags + flags + targets))


def execute_bazel_test(bazel_binary, flags, targets, bep_file):
  if not targets:
    return 0
  print_expanded_group("Test")
  num_jobs = str(multiprocessing.cpu_count())
  common_flags = ["--curses=yes", "--color=yes", "--keep_going", "--verbose_failures",
                  "--flaky_test_attempts=3", "--build_tests_only",
                  "--jobs=" + num_jobs, "--local_test_jobs=" + num_jobs,
                  "--build_event_json_file=" + bep_file]
  return execute_command([bazel_binary, "test"] + common_flags + flags + targets)


def fail_if_nonzero(exitcode):
  if exitcode is not 0:
    exit(exitcode)


def upload_test_logs(bep_file, tmpdir):
  if not os.path.exists(bep_file):
    return
  test_logs = test_logs_to_upload(bep_file, tmpdir)
  if test_logs:
    cwd = os.getcwd()
    try:
      os.chdir(tmpdir)
      print_collapsed_group("Uploading test logs")
      for logfile in test_logs:
        relative_path = os.path.relpath(logfile, tmpdir)
        fail_if_nonzero(execute_command(["buildkite-agent", "artifact", "upload",
                                         relative_path]))
    finally:
      os.chdir(cwd)


def test_logs_to_upload(bep_file, tmpdir):
  failed = test_logs_for_status(bep_file, status="FAILED")
  timed_out = test_logs_for_status(bep_file, status="TIMEOUT")
  flaky = test_logs_for_status(bep_file, status="FLAKY")
  # Rename the test.log files to the target that created them
  # so that it's easy to associate test.log and target.
  new_paths = []
  for label, test_logs in (failed + timed_out + flaky):
    attempt = 0
    if len(test_logs) > 1:
      attempt = 1
    for test_log in test_logs:
      new_path = test_label_to_path(tmpdir, label, attempt)
      os.makedirs(os.path.dirname(new_path), exist_ok=True)
      copyfile(test_logs, new_path)
      new_paths.append(new_path)
      attempt = attempt + 1
  return new_paths


def test_label_to_path(tmpdir, label, attempt):
  # remove leading //
  path = label[2:]
  path = path.replace(":", "/")
  if attempt == 0:
    path = os.path.join(path, "test.log")
  else:
    path = os.path.join(path, "attempt_" + str(attempt) + ".log")
  return os.path.join(tmpdir, path)


def test_logs_for_status(bep_file, status):
  targets = []
  raw_data = ""
  with open(bep_file) as f:
    raw_data = f.read()
  decoder = json.JSONDecoder()

  pos = 0
  while pos < len(raw_data):
    bep_obj, size = decoder.raw_decode(raw_data[pos:])
    if "testResult" in bep_obj:
      test_target = bep_obj["id"]["testResult"]["label"]
      test_result = bep_obj["testResult"]
      if test_result["status"] == status:
        outputs = test_result["testActionOutput"]
        test_logs = []
        for output in outputs:
          if output["name"] == "test.log":
            test_logs.append(urlparse(output["uri"]).path)
        if test_logs:
          targets.append((test_target, test_logs))
    pos += size + 1
  return targets


def execute_command(args, shell=False):
  print(" ".join(args))
  res = subprocess.run(args, shell=shell)
  return res.returncode


def print_project_pipeline(platform_configs, project_name, http_config,
                           git_repository, use_but):
  pipeline_steps = []
  for platform, config in platform_configs.items():
    step = runner_step(platform, project_name, http_config, git_repository,
                       use_but)
    pipeline_steps.append(step)

  print_pipeline(pipeline_steps)


def runner_step(platform, project_name=None, http_config=None,
                git_repository=None, use_but=False, save_but=False, build_only=False,
                test_only=False):
  command = python_binary() + " bazelci.py runner --platform=" + platform
  if http_config:
    command = command + " --http_config=" + http_config
  if git_repository:
    command = command + " --git_repository=" + git_repository
  if use_but:
    command = command + " --use_but"
  if save_but:
    command = command + " --save_but"
  if build_only:
    command = command + " --build_only"
  if test_only:
    command = command + " --test_only"
  label = create_label(platform_name(platform),
                       project_name, build_only, test_only)
  return """
  - label: \"{0}\"
    command: \"{1}\\n{2}\"
    agents:
      - \"os={3}\"""".format(label, fetch_bazelcipy_command(), command, platform)


def print_pipeline(steps):
  print("steps:")
  for step in steps:
    print(step)


def wait_step():
  return """
  - wait"""


def http_config_flag(http_config):
  if http_config is not None:
    return "--http_config=" + http_config
  return ""


def fetch_bazelcipy_command():
  return "curl -s {0} -o bazelci.py".format(bazelcipy_url())


def upload_project_pipeline_step(project_name, git_repository, http_config):
  pipeline_command = ("{0} bazelci.py project_pipeline --project_name=\\\"{1}\\\" " +
                      "--use_but --git_repository={2}").format(python_binary(), project_name,
                                                               git_repository)
  if http_config:
    pipeline_command = pipeline_command + " --http_config=" + http_config
  pipeline_command = pipeline_command + " | buildkite-agent pipeline upload"

  return """
  - label: \"Setup {0}\"
    command: \"{1}\\n{2}\"
    agents:
      - \"pipeline=true\"""".format(project_name, fetch_bazelcipy_command(),
                                    pipeline_command)


def create_label(platform_name, project_name=None, build_only=False,
                 test_only=False):
  label = ""
  if build_only:
    label = "Build "
  if test_only:
    label = "Test "
  if project_name:
    label = label + "{0} ({1})".format(project_name, platform_name)
  else:
    label = label + platform_name
  return label


def bazel_build_step(platform, project_name, http_config=None,
                     build_only=False, test_only=False):
  pipeline_command = python_binary() + " bazelci.py runner"
  if build_only:
    pipeline_command = pipeline_command + " --build_only --save_but"
  if test_only:
    pipeline_command = pipeline_command + " --test_only"
  if http_config:
    pipeline_command = pipeline_command + " --http_config=" + http_config
  label = create_label(platform_name(platform), project_name, build_only=build_only,
                       test_only=test_only)
  pipeline_command = pipeline_command + " --platform=" + platform

  return """
  - label: \"{0}\"
    command: \"{1}\\n{2}\"
    agents:
      - \"os={3}\"""".format(label, fetch_bazelcipy_command(),
                             pipeline_command, platform)


def publish_bazel_binaries_step():
  command = python_binary() + " bazelci.py publish_binaries"
  return """
  - label: \"Publish Bazel Binaries\"
    command: \"{0}\\n{1}\"
    agents:
      - \"pipeline=true\"""".format(fetch_bazelcipy_command(), command)


def print_bazel_postsubmit_pipeline(configs, http_config):
  if not configs:
    eprint("Bazel postsubmit pipeline configuration is empty.")
  if set(configs.keys()) != set(supported_platforms()):
    eprint("Bazel postsubmit pipeline needs to build Bazel on all " +
           "supported platforms.")

  pipeline_steps = []
  for platform, config in configs.items():
    pipeline_steps.append(bazel_build_step(platform, "Bazel",
                                           http_config, build_only=True))
  pipeline_steps.append(wait_step())

  # todo move this to the end with a wait step.
  pipeline_steps.append(publish_bazel_binaries_step())

  for platform, config in configs.items():
    pipeline_steps.append(bazel_build_step(platform, "Bazel",
                                           http_config, test_only=True))
  for project, config in downstream_projects().items():
    git_repository = config["git_repository"]
    http_config = config.get("http_config", None)
    pipeline_steps.append(upload_project_pipeline_step(project,
                                                       git_repository, http_config))

  print_pipeline(pipeline_steps)


def bazelci_builds_download_url(platform, build_number):
  return "https://storage.googleapis.com/bazel-builds/artifacts/{0}/{1}/bazel".format(platform, build_number)


def bazelci_builds_upload_url(platform, build_number):
  return "gs://bazel-builds/artifacts/{0}/{1}/bazel".format(build_number, platform)


def bazelci_builds_metadata_url():
  return "gs://bazel-builds/metadata/latest_fully_tested.json"


def latest_generation_and_build_number():
  output = None
  attempt = 0
  while attempt < 5:
    output = subprocess.check_output(
        ["gsutil", "stat", bazelci_builds_metadata_url()])
    match = re.search("Generation:[ ]*([0-9]+)", output.decode("utf-8"))
    if not match:
      eprint("Couldn't parse generation. gsutil output format changed?")
    generation = match.group(1)

    match = re.search("Hash \(md5\):[ ]*([^\s]+)", output.decode("utf-8"))
    if not match:
      eprint("Couldn't parse md5 hash. gsutil output format changed?")
    expected_md5hash = base64.b64decode(match.group(1))

    output = subprocess.check_output(
        ["gsutil", "cat", bazelci_builds_metadata_url()])
    hasher = hashlib.md5()
    hasher.update(output)
    actual_md5hash = hasher.digest()

    if expected_md5hash == actual_md5hash:
      break
    attempt = attempt + 1
  info = json.loads(output.decode("utf-8"))
  return (generation, info["build_number"])


def sha256_hexdigest(filename):
  sha256 = hashlib.sha256()
  with open(filename, 'rb') as f:
    for block in iter(lambda: f.read(65536), b''):
      sha256.update(block)
  return sha256.hexdigest()


def try_publish_binaries(build_number, expected_generation):
  tmpdir = None
  try:
    tmpdir = tempfile.mkdtemp()
    info = {
        "build_number": build_number,
        "git_commit": os.environ["BUILDKITE_COMMIT"],
        "platforms": {}
    }
    for platform in supported_platforms():
      bazel_binary_path = download_bazel_binary(tmpdir, platform)
      fail_if_nonzero(execute_command(["gsutil", "cp", "-a", "public-read", bazel_binary_path,
                                       bazelci_builds_upload_url(platform, build_number)]))
      info["platforms"][platform] = {
          "url": bazelci_builds_download_url(platform, build_number),
          "sha256": sha256_hexdigest(bazel_binary_path),
      }

    info_file = os.path.join(tmpdir, "info.json")
    with open(info_file, mode="w", encoding="utf-8") as fp:
      json.dump(info, fp)
    exitcode = execute_command(["gsutil", "-h", "x-goog-if-generation-match:" + expected_generation,
                                "-h", "Content-Type:application/json", "cp", "-a",
                                "public-read", info_file, bazelci_builds_metadata_url(platform)])
    return exitcode == 0
  finally:
    if tmpdir:
      shutil.rmtree(tmpdir)


def publish_binaries():
  '''
  Publish Bazel binaries to GCS.
  '''
  attempt = 0
  while attempt < 5:
    latest_generation, latest_build_number = latest_generation_and_build_number()

    current_build_number = os.environ.get("BUILDKITE_BUILD_NUMBER", None)
    if not current_build_number:
      eprint("Not running inside Buildkite")
    current_build_number = int(current_build_number)
    if current_build_number <= latest_build_number:
      print(("Current build '{0}' is not newer than latest published '{1}'. " +
             "Skipping publishing of binaries.").format(current_build_number,
                                                        latest_build_number))
      break

    if try_publish_binaries(current_build_number, latest_generation):
      print("Successfully updated '{0}' to binaries from build {1}."
            .format(bazelci_builds_metadata_url(), current_build_number))
      break
    attempt = attempt + 1


if __name__ == "__main__":
  parser = argparse.ArgumentParser(
      description='Bazel Continuous Integration Script')

  subparsers = parser.add_subparsers(dest="subparsers_name")
  bazel_postsubmit_pipeline = subparsers.add_parser(
      "bazel_postsubmit_pipeline")
  bazel_postsubmit_pipeline.add_argument("--http_config", type=str)
  bazel_postsubmit_pipeline.add_argument("--git_repository", type=str)

  project_pipeline = subparsers.add_parser("project_pipeline")
  project_pipeline.add_argument("--project_name", type=str)
  project_pipeline.add_argument("--http_config", type=str)
  project_pipeline.add_argument("--git_repository", type=str)
  project_pipeline.add_argument(
      "--use_but", type=bool, nargs="?", const=True)

  runner = subparsers.add_parser("runner")
  runner.add_argument("--platform", action="store",
                      choices=list(supported_platforms()))
  runner.add_argument("--http_config", type=str)
  runner.add_argument("--git_repository", type=str)
  runner.add_argument("--use_but", type=bool, nargs="?", const=True)
  runner.add_argument("--save_but", type=bool, nargs="?", const=True)
  runner.add_argument("--build_only", type=bool, nargs="?", const=True)
  runner.add_argument("--test_only", type=bool, nargs="?", const=True)

  runner = subparsers.add_parser("publish_binaries")

  args = parser.parse_args()

  if args.subparsers_name == "bazel_postsubmit_pipeline":
    configs = fetch_configs(args.http_config)
    print_bazel_postsubmit_pipeline(configs.get("platforms", None),
                                    args.http_config)
  elif args.subparsers_name == "project_pipeline":
    configs = fetch_configs(args.http_config)
    print_project_pipeline(configs.get("platforms", None), args.project_name,
                           args.http_config, args.git_repository, args.use_but)
  elif args.subparsers_name == "runner":
    configs = fetch_configs(args.http_config)
    execute_commands(configs.get("platforms", None)[args.platform],
                     args.platform, args.git_repository, args.use_but, args.save_but,
                     args.build_only, args.test_only)
  elif args.subparsers_name == "publish_binaries":
    publish_binaries()
  else:
    parser.print_help()